Each layer of a silver halide photographic material contains, in general, various kinds of photographic additives, such as coupler, ultra-violet absorbent, anti-oxidant, stabilizer, color-stain inhibitor, anti-fogging agent, dye, etc.; and various methods have heretofore been proposed for fixation of specific photographic additivess in a specific layer comprising gelatin or the like hydrophilic binder.
For instance, one prior art method is disclosed, for example, in U.S. Pat. Nos. 2,322,029, 2,360,289, 2,533,514 and 2,801,170, where a hydrophobic coupler having an oil-soluble group and a photographically useful group is dissolved in a solvent having a high boiling point, and the resulting solution is dispersed in a hydrophilic polymer solution to obtain a coupler-dispersion, which is coated on a photographic support. Another prior art method is disclosed, for example, in Japanese Patent Application (OPI) No. 59943/76 (The term "OPI" as used herein refers to a published unexamined Japanese Patent Application.), where a hydrophobic coupler having an oil-soluble group and a photographically useful group is dissolved in a water-compatible organic solvent and an aqueous polymer latex is gradually added to the resulting solution and admixed therewith to incorporate said hydrophobic coupler in said latex particles, and then the mixture obtained is dispersed in a hydrophilic polymer and then coated on a photographic support.
However, these prior art methods include some troublesome defects as mentioned below. The former method requires an emulsification step requiring a large amount of energy, and the coupler, etc., are often deteriorated during said step, and thus, this is not always advantageous. On the other hand, in the latter method, the amount of the hydrophobic coupler to be incorporated in the latex particles must inevitably be limited in order to prevent the aggregation of said latex particles, and, therefore, desired photographic characteristics can not always be obtained.
In addition to said above prior art methods, still another methods are known, as disclosed, e.g., in Research Disclosure, No. 190, pp. 65-66 (1980), U.S. Pat. Nos. 3,926,436 and 4,397,943, and German Pat. No. 1,547,863, where coupler, ultra-violet absorbent and stabilizer are added, each in the form of a water-soluble polymer, to a hydrophilic polymer binder, and the solution obtained is coated on a photographic support. However, this method is also defective in that the water-soluble polymers are not rendered sufficiently non-diffusive and so these are apt to flow out in a developer during development. In order to provide non-diffusiveness to a polymer, water-soluble polymers have been developed, having a reactive group such as vinylsulfone group, active ester group, active methylene group, primary amino group, epoxy group, etc. together with a photographically useful group, said reactive group being able to be cross-linked with gelatin directly or via a hardening agent, for example, as described in Research Disclosure, No. 17825 (1979), U.S. Pat. Nos. 4,215,195, 3,859,096 and 3,625,694 and Japanese Patent Application (OPI) Nos. 27139/83 and 142524/81.
However, said photographically useful group-containing water-soluble reactive polymer do not have sufficient reactivity with gelatin or a hardening agent, and so to provide complete non-diffusiveness to said polymers is difficult. For example, in the case of a water-soluble polymer which has a photographically useful group a coupler residue capable of forming a dye by coupling with an oxidation product of an aromatic primary amine developing agent, if said polymer is not sufficiently made non-diffusive, color stain is apt to occur, and furthermore the polymer often flows out during development treatment, resulting in decrease of the density of the formed images. In the case of a water-soluble polymer having a residue derived from a reductive color stain-inhibitor as a photographically useful group, if the non-diffusiveness of said polymer is insufficient, the polymer also includes problems of color-stain and decrease of the density of the formed images.
In addition, said conventional reactive groups such as vinylsulfone group, active ester group, active methylene group and epoxy group are per se hydrophobic. Accoridngly, if the polymers themselves containing such hydrophobic group are to be made water-soluble, it is necessary to copolymerize them with a substantial amount of hydrophilic monomer, in addition to a monomer having said reactive group or a monomer having a photographically useful group. Under the situation, the ratio of the amount of said monomers having the reactive group or a photographically useful group must be limited. However, if the ratio of the reactive group-containing monomer is made small, sufficient non-diffusiveness cannot be attained; and if the ratio of the photographically useful group-containing monomer is made small, sufficient photographic characteristics cannot be attained. These have been troublesome problems.